September 7, 2006

Physicists at the U.S. Department of Energy's Argonne National Laboratory have devised a potentially groundbreaking theory demonstrating how to control the spin of particles without using superconducting magnets — a development that could advance the field of spintronics and bring scientists a step closer to quantum computing.

Spintronics, also known as spin electronics, is an emerging technology that looks to develop devices that exploit the quirky world of quantum physics, or physics at the incredibly small atomic level, particularly the up-or-down spin property of electrons. Conventional electronics use the charge of the electron. Spintronic devices would use both the spin and charge, achieving new functionality.

Scientists across the globe are racing to develop the spintronics field. It could revolutionize the computing industry with chips that are more versatile and exponentially more powerful than today's most cutting-edge technology.

Physicists Dimitrie Culcer and Roland Winkler, along with Christian Lechner of Regensburg University, Germany, will publish their theoretical findings in the Sept. 8 issue of Physical Review Letters. Culcer and Winkler are at Northern Illinois University, in addition to their affiliation with the Advanced Photon Source at Argonne.

“Our research illuminates a new pathway for generating and manipulating the spin in semiconductors,” Winkler said. “This is important, because the use of bulky superconducting magnets would be impractical in most devices.”

The physicists theorize that spin can be induced and manipulated by running a current through gallium arsenide, a common semiconductor, in what is known as spin-3/2 hole systems, which previously have been little studied. Hole systems are “missing electrons,” while the fraction 3/2 refers to the magnitude of the spin. Spin-3/2 hole systems are created in semiconductors by “doping” — introducing impurities that have one less electron compared to the host material.

Geometry also must play a crucial role in spin manipulation, according to the researchers. They propose development of a nano-sized and L-shaped device that allows for the exploitation of the newly discovered effects in spin-3/2 hole systems.

“Spin polarization is achieved as the current flows around the corner,” Winkler said.

“We believe we've discovered a much simpler way for inducing spin polarization,” he added. “We don't need a big magnet. The only requirement in our case is an electrical current in the sample, which is much easier to achieve than putting the sample in a magnetic coil. For an electrical current, you only need two contacts.”

Culcer said the researchers hope the publication will raise awareness of new and exciting physics that can be accomplished in spin-3/2 hole systems.

“We do basic research and do not work directly on information technology,” Culcer said. “But researchers working on quantum computing are primarily interested in spin systems. For the past 50 years, scientists have intensely studied what's known as spin-1/2 systems.

“One of our primary goals with this paper was to demonstrate what could be accomplished with spin-3/2 systems,” he said. “We hope to point scientists in a direction that offers the possibility of new applications and hopefully ways of manipulating information in the future.”

Related Stories

A fast-moving pulsar appears to have punched a hole in a disk of gas around its companion star and launched a fragment of the disk outward at a speed of about 4 million miles per hour. NASA's Chandra X-ray Observatory is ...

Satellite communications could be streamlined by light and inexpensive antennas that have been developed by SWISSto12. This EPFL spin-off has just signed a major contract with the European Space Agency to develop its metal-plated ...

Ultracold atoms in the so-called optical lattices, which are generated by crosswise superposition of laser beams, have been proven to be one of the most promising tools for simulating and understanding the behaviour of many-body ...

Dip a beaker into any portion of the world's oceans, and you're likely to pull up a swirling mix of planktonic inhabitants. The oceans are teeming with more than 5,000 species of phytoplankton—microscopic plants in a kaleidoscope ...

(Phys.org)—Stuart Kauffman, from the University of Calgary, and several of his colleagues have recently published a paper on the Arxiv server titled 'Quantum Criticality at the Origins of Life'. The idea of a quantum criticality, ...

Recommended for you

Traditional computers manipulate electrons to turn our keystrokes and Google searches into meaningful actions. But as components of the computer processor shrink to only a few atoms across, those same electrons become unpredictable ...

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

The laws of classical mechanics are independent of the direction of time, but whether the same is true in quantum mechanics has been a subject of debate. While it is agreed that the laws that govern isolated quantum systems ...

(Phys.org)—In an attempt to harvest the kinetic energy of airflow, researchers have demonstrated the ability to harvest energy directly from the vibrations of a flexible, piezoelectric beam placed in a wind tunnel. While ...